xppaut: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/xppaut - from package: xppaut

You may install the required package with command apt-get install {package}

Error in other languages:
xppaut: bevel nie gevind nie
xppaut: comandă negăsită
xppaut: comando não encontrado
xppaut: commande introuvable
xppaut: command not found
xppaut: käsku ei ole
xppaut: không tìm thấy lệnh
xppaut: komanda nerasta
xppaut: Kommando nicht gefunden.
xppaut: kommandot finns inte
xppaut: komut yok
xppaut: nie znaleziono polecenia
xppaut: níor aimsíodh an t-ordú
xppaut: no se encontró la orden
xppaut: no s'ha trobat l'ordre
xppaut: opdracht niet gevonden
xppaut: parancs nem található
xppaut: perintah tidak ditemukan
xppaut: príkaz nenájdený
xppaut: příkaz nenalezen
xppaut: команда не найдена
xppaut: командата не е открита
xppaut: 命令找不到
xppaut: コマンドが見つかりません